An electrostatic coating system in which the water fed from a water feeding device is purified water, and a coating material in a coating material cartridge installed in a coating gun is pushed out by the purified water and sprayed from a coating material nozzle to apply a coating is disclosed in Japanese Patent Application Laid-Open Publication No. 2006-346596.
FIG. 18 hereof shows the coating system disclosed in the 2006-346596 publication.
The coating system 200 is provided with a purified water feeding device 201 and a coating gun 211.
The purified water feeding device 201 is composed of a water feeding device 204, a discharge quantity control device 205, and a purified water production device 206.
The coating gun 211 is composed of a coating gun main body 212 and a coating material tank unit 213 as a coating material cartridge that is detachably attached to the coating gun main body 212. The coating material tank unit 213 is provided with a coating material chamber 215 for storing a coating material, a coating material nozzle 216 communicated with the coating material chamber 215, and an ejection liquid chamber 217 to which the abovementioned purified water is fed. The coating material chamber 215 and the ejection liquid chamber 217 are partitioned from each other by a piston 218.
When purified water is fed to the ejection liquid chamber 217 from the purified water feeding device 201, the purified water pushes the piston 218 and ejects the coating material inside the coating material chamber 215, and causes the coating material to be sprayed from the coating material nozzle 216.
However, in the coating system described above, the coating material tank unit 213 must be replaced at each coating operation when handling an electrically conductive coating material of a color frequently used for coating, the amount of labor involved in coating increases, and the work of coating is inefficient. Cost therefore increases.